Push side pool cleaners are distinguished from suction side cleaners, for various reasons known in the art; an example of a push side cleaner is described in South African patent 85/0648, granted to Alopex Industries, marketed as the “POLARIS” (trademark).
Whereas suction side cleaners have an effective wiping or rubbing action on the pool surfaces, this is a shortcoming with push side pool cleaners of the present art which run on wheels with a venturi passage passing over the pool surfaces with a clearance between the mouth of the venturi and the pool surface.
Again, whereas suction side pool cleaners have few moving parts, the cleaner moving over the pool surfaces under impulsion of intermittent water flow caused by an oscillating tongue, or a suction tube whose wall collapses intermittently, for example, certain push side pool cleaners of the art have the disadvantage that they are moved by means of a water turbine driving the wheels through a drive train consisting of many gears and shafts.
Also, whereas suction side cleaners remove very small particles from the pool because the particles picked up are passed through the main pool filter, push side pool cleaners of the art do not pass particles through the main pool filter, but through a bag filter attached to the cleaner; dust size particles pass the apertures of bag type filters to re-enter the pool water, so that these cleaners must rely on stirring up these dust size particles so that they remain sufficiently in suspension to be drawn into the pool weir and thence to the main pool filter.
Whereas suction side cleaners are “add on” products, which the owner of an existing pool and filtering system can add on without technical assistance, most push side cleaners of the present art are initially set up by a technically capable person, where they are connected to a booster pump in the main pool filter circulation system, or into a dedicated water circulation system. Hence push side pool cleaners of the art tend to be sold via contractors who are building a pool and circulation system.
Although push side pool cleaners do have potential for less interference with the desirable randomness of movement over the pool surfaces, due to a smaller diameter hose being acceptable, than suction side cleaners, much of this potential advantage is lost by the wheeled drive of these cleaners of the push side cleaner art which tend to provide straight line travel. The POLARIS cleaner has three wheels asymmetrically arranged to try to reduce this effect, for example. There is a continuing need in the art for better randomness of movement of the cleaner over the pool surfaces, leading to better cleaning.
The push side water flow is given a bypass valve at the pool side allowing water flow to the cleaner to be adjusted by increasing or decreasing the bypass, so as to get an acceptable speed of movement of the cleaner over the pool surfaces. A disadvantage of this arrangement of the art is that the energy of the bypassed flow is discarded.
Finally, all present pool cleaners have limitations as to the shallowness at which they will operate and as to their ability to negotiate formations like stairs in pools without becoming stuck in one position. It is desirable that pool cleaners work in shallower regions and thus negotiate formations like stairs better.
Thus there exists a need to address these limitations and problems in push side cleaners of the art at least to some extent.